merge: 合并 main 分支到 test，解决 config 和 modelWhitelist 冲突

- config.go: 保留 Sora 配置，合入 SubscriptionCache 配置
- useModelWhitelist.ts: 同时保留 soraModels 和 antigravityModels

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/internal/handler/dto/mappers.go

@@ -215,17 +215,6 @@ func AccountFromServiceShallow(a *service.Account) *Account {
 		}
 	}
 
-	if scopeLimits := a.GetAntigravityScopeRateLimits(); len(scopeLimits) > 0 {
-		out.ScopeRateLimits = make(map[string]ScopeRateLimitInfo, len(scopeLimits))
-		now := time.Now()
-		for scope, remainingSec := range scopeLimits {
-			out.ScopeRateLimits[scope] = ScopeRateLimitInfo{
-				ResetAt:      now.Add(time.Duration(remainingSec) * time.Second),
-				RemainingSec: remainingSec,
-			}
-		}
-	}
-
 	return out
 }